SE457598B - PROTEST FOR HOPE SPLITING OF NERVENDENDS - Google Patents

Abstract

An implantable prosthesis for splicing nerve ends comprises an elongate prosthetic element (1) of bioresorbable material provided with a plurality of channels (2) which extend between the ends of the prosthetic element (1) and are intended to serve as growth rooms for one or more nerve fibres or bundles thereof.

Description

Thus, in one embodiment, the nerve joint prosthesis may consist of an elongate cylindrical element provided with a large number of parallel continuous channels or bores.

The cross-sectional dimensions of the channels must of course be sufficient to allow the passage of the nerve fibers, so they must have a minimum cross-sectional dimension of about 1 pm. Thus, for example, for circular channels, a suitable diameter may be from about 5 to about 150 microns, especially about 5 to about 20 microns.

As will be readily appreciated, in view of the compaction arrangement in which the nerve trees are present in the nerve trunks, the above-mentioned channels in the splice prosthesis should be arranged rather tightly, which means a relatively high degree of perforation of the cross-section of the prosthetic element. Ideally, each nerve fiber should have its own channel, which, however, should hardly be possible to achieve in practice.

The term "bioresorbable material" in the present context is understood to mean substantially water-insoluble, non-toxic, tissue-friendly materials which can be degraded and completely resorbed in the body without giving rise to scar tissue or toxic degradation products.

Suitable bioresorbable materials for the purposes of the present invention may be readily selected by those skilled in the art, for example from those which are either commercially available or have been described in the literature or will be available in the future. Examples of bloresorbable materials are polymers based on polyglycolic acid (PGA), copolymers of glycolic acid and lactic acid, copolymers of lactic acid and ε-aminocaproic acid, and various lactide polymers. PGA esters are available e.g. described in U.S. Patent 3 # 63,658. Copolymers between glycolic acid and lactic acid are described, for example, in U.S. Patent 3,982,5143, and homo- and copolymers of lactic acid are described e.g. in U.S. Patent 3,636,956. Examples of commercially available materials are Vicryß (a copolymer of 9096 glycolic acid and 1096 lactic acid, sold by Ethicon, Sommerville, NY, USA - also known as Polyglactin 910) and Dexon (Davies Island: Geck , Pearl River, NY, USA). Additional examples are polydesoxazone (PDS) (Ethicon, USA), polyhydroxybutyric acid (PHB), copolymers of hydroxybutyric acid and hydroxyvaleric acid, polyester of succinic acid, and crosslinked hyaluronic acid. Of course, mixtures of the above-mentioned materials can also be considered, for example a mixture of PHB and Vicry.

The person skilled in the art should readily modify such bioresorbable materials according to the current needs, with regard to parameters discussed below such as porosity, resorption time, etc.

The bioresorbable material is preferably porous, especially microporous, to allow penetration of fluids.

The strength of the prosthetic material need only be sufficient to withstand the usually relatively low stress load on the spliced nerve.

The resorption time of the prosthesis material must of course be sufficient for the growth of the nerve fibers, and thus the splicing of the nerve, to be completed before the prosthesis has been resorbed to any significant extent. This time is of course due to e.g. on the distance that the nerve fibers are to grow in the individual case, ie. the distance between the nerve endings, but the resorption time should usually be longer in about 2 months.

Optionally, one or more growth promoting agents may be incorporated into the prosthetic material, such as nerve growth factor (NGF).

A nerve joint prosthesis according to the invention can be manufactured in a number of different ways. For example, it can be made by bundling a number of thin fibers of bioresorbable material and then optionally elongating them to achieve the desired gap or channel dimensions between the fibers. Optionally, the fibers used may be hollow fibers. Such a fiber assembly may optionally be held together by a resorbable outer shell.

Alternatively, the splice prosthesis can be made by laser drilling in a solid prosthetic element of bioresorbable material to receive the required channels, possibly accompanied by longitudinal extension of the prosthetic element.

During implantation, the ends of the nerve joint prosthesis can be attached to the nerve stumps in question in any suitable way, e.g. by sewing or gluing with a suitable resorbable suture resp. resorbable glue.

Preferably, the splice prosthesis is provided in the form of larger lengths, possibly on a roll if the flexibility so allows, from which the suitable prosthesis length is cut at the time of use. In the following, the invention will be described in more detail with reference to a particular embodiment thereof with reference to the accompanying drawings, in which Fig. 1 is a perspective view of an embodiment of a nerve joint prosthesis according to the invention, and Fig. 2 is a, partly transparent, schematic perspective view of the nerve joint prosthesis in Fig. 1 applied to a severed nerve.

The nerve joint prosthesis shown in Fig. 1, which is generally denoted by the reference numeral 1, consists of a cylinder of suitable bioresorbable material, e.g. a microporous one of 8596 PHB and 1596 Vicry, which is provided with a large number of parallel separated channels or bores 2, which for the sake of clarity are shown considerably enlarged and therefore relatively few in number. A suitable diameter of the bores can be about 5-20 μm. Although it is advantageous that the splice prosthesis element 1 has substantially the same cross-sectional dimension as the nerve to be spliced, it can be considerably coarser than the nerve without it in any significant way impeding the objects of the invention. As an example of a suitable diameter of the nerve joint prosthesis can be mentioned about 1 to about 20 mm.

The nerve joint prosthesis 1 is suitably provided in larger lengths, from which one cuts to the required length for the particular application at the time of use.

Referring to Fig. 2, in use, a splice prosthesis 1 of suitable length is applied to a severed nerve, the two stumps of which are denoted by the reference numeral 3, and which have a plurality of nerve wires or axons schematically indicated by ll. Then, in the illustrated case, the prosthesis 1 is attached to the two nerve endings 3 by means of two attachment sleeves 5 'of bioresorbable material, e.g. the same material as in the prosthesis 1. In this case, each fastening sleeve 5 is passed over a nerve end 3 and the adjacent end of the prosthesis 1, after which it is fixed to the two parties in a suitable manner, e.g. by sewing with resorbable suture or gluing with resorbable glue in a manner known per se.

In place, the channels 2 in the prosthetic element 1 will serve as delimited growth chambers or zones for individual nerve fibers I: or the nerve bundles or buritain. At the same time, the prosthesis material is slowly resorbed in the body, however, the resorption time is long enough for the nerve to grow together before the intended function of the prosthesis is lost through resorption. Usually, however, the resorption time should be at least about 2 months.

The invention is of course not limited to the embodiment described above and especially shown, but many modifications and changes can be made within the scope of the general inventive concept, as stated in the claims.

Claims (7)

10 15 20 457 598 5 PATENT REQUIREMENTS A prosthesis for splicing nerve endings, comprising an elongate prosthetic element (1) of bioresorbable material, characterized in that it has a plurality of channels (2) extending between the ends of the prosthesis element (1) and are intended to serve as a growth space. for one or more individual nerve fibers (4) or bundles thereof. Prosthesis according to claim 1, characterized in that the channels (2) are substantially completely separated from each other. Prosthesis according to claim 1 or 2, characterized in that the channels (2) are substantially straight and parallel to the longitudinal axis of the prosthesis. Prosthesis according to any one of claims 1 to 3, characterized in that the channels (2) have a cross-sectional dimension of about 5- 150 μm, preferably about 5 to about 20 μm. A prosthesis according to any one of claims 1 to 4, characterized in that it has a resorption time of at least about 2 months. Prosthesis according to one of Claims 1 to 5, characterized in that it comprises two fastening sleeves (5) of bioresorbable material for fixing the prosthesis (1) to the nerve endings (3). Prosthesis according to one of Claims 1 to 6, characterized in that the prosthesis material delimiting the channels (2) is microporous.